Gay and bisexual men (GBM) and other men who have sex with men (MSM) accounted for 63% of all new HIV diagnoses in 2010 -they are among the only population in which infections are actually rising. The syndemics model has been applied to MSM finding considerable empirical support for a model in which several specific co-occurring psychosocial health problems (e.g., depression, substance use, trauma from childhood sexual abuse, intimate partner violence) compound risk for HIV. Yet this model does not account for resilience in the face of syndemic factors-there are GBM who experience syndemics and yet do not engage in hazardous (i.e., HIV risk) behavior. Yet, resilience too is not well understood among GBM. The proposed study builds from the syndemics framework by investigating patterns of resilience in a national US sample of GBM. We have partnered with Harris Interactive, Inc., a research firm that maintains the largest and most comprehensive database of GBM, to identify a national sample of 1,000 GBM to participate in a 3- year longitudinal study (Baseline, 12-, 24-, 36-months) investigating patterns and correlates of syndemic, protective, and resilient factors. We propose to collect behavioral and biological outcomes (at-home HIV and STI testing). We will: (1) Determine patterns and prevalence of syndemic factors and risk behavior in a national sample of GBM; (2) Conduct qualitative interviews with a subsample of participants to identify new/unmeasured mechanisms of resilience and to contextualize our quantitative data (Baseline and 36- months); and (3) Longitudinally track trajectories in resilience, syndemics, and HIV and STI incidence to identify psychosocial and behavioral factors associated with these changing trajectories. Our methodological design-including the use of a national sample, longitudinal assessments, biological testing for HIV and STIs-enhances this study's external validity and thus the impact of our findings. And by tracking patterns in syndemics and resilience, this study will inform (1) the development of the next generation of HIV prevention methods and (2) potential ways to improve established CDC DEBIs. Our application addresses an important problem and barrier to progress in the field (a strengths-based approach to HIV prevention among GBM that goes above and beyond general protective factors to examine resilient factors among men with high risk for hazardous behavior). It has potential to improve scientific knowledge regarding HIV prevention efforts with GBM. And understanding resilience in the face of syndemics can change the conceptual approach, treatments, services, and interventions for a population that remains in critical need.